It is well known to provide electric heating systems for ski boots and other footwear. Such devices are normally made available as kits for installation by the user, into footwear. In one such arrangement as shown in U.S. Pat. No. 4,507,877, issued on Apr. 2, 1985 to Vaccari, et al., batteries which provide the power for the heater element are located within a storage compartment accommodated inside the sole of a boot, with a control switch in the form of a toggle switch mounted at the top on the outside of the boot and electrically connected in a circuit with the battery. Other devices wherein the shoe incorporates batteries within it are shown in U.S. Pat. Nos. 4,798,933, issued Jan. 17, 1989 to Annovi and 3,977,093, issued Aug. 31, 1976 to Santroch. In both of these devices, a switching arrangement is in the form of a pushbutton switch is built into a portion of the shoe and either is manually operable or operable by the wearer moving his foot to actuate it.
Battery packs have been mounted externally of footwear wherein the heating elements are connected by electrical wires which run from the footwear externally to a battery pack. Such a device is shown, for example, in U.S. Pat. No. 4,088,971 issued Mar. 28, 1978 to Leeper. In that device, a battery pack consisting of two hinged halves for enclosing the battery is held together by a strap which is used to mount the battery pack to the calf of the leg of the wearer. The battery pack is provided with an externally pivotable switch which can be swung from a contact engaging position to a contact disengaging position. Being mounted externally of the battery pack such a device can be subjected to malfunction and damage because it is on the external surface of the battery pack and may be made inoperable due to rusting or dirt accumulation.
It has been further suggested to provide a battery pack which can be mounted on the heel area of a boot. Such a device is shown in U.S. Pat. No. 3,859,496, issued on Jan. 7, 1975 to Giese wherein a slide is mounted externally of the boot for supporting a battery carrying case. The slide is provided with electrical contacts to be engaged with the battery contacts and is electrically connected to the heating element within the boot. It is clear that in such an arrangement the slide contact means is subjected to the elements and may be damaged to the extent that the device becomes inoperable. In any event, while being worn, such a device is rather awkward to operate since the turning of the heater on and off is accomplished by positioning of the battery on the slide, and this requires the wearer to turn around and try to observe the mating of the battery elements with the slide contact.